Major cyber attacks that could cripple Britain’s energy supplies, nuclear power stations and defence industry have doubled in a year, GCHQ has warned.

Spy chiefs said Britain’s listening post was identifying 200 ‘significant’ cyber attacks a month – around seven a day – compared with just 100 a month last year.

Criminals, terror cells and hostile foreign states are using cyber technology to target critical infrastructure in a bid to bring chaos to the UK or steal the country’s industrial and military secrets.

Ciaran Martin, director general for cyber-security at GCHQ, drummed home how the UK faced sophisticated and continual threats online every single day.

He said: ‘These are attacks that are of significance to national security. That is either because of who the aggressor or the victim is or because of the nature of the attack.’

Mr Martin reinforced remarks he made in the summer when he said the cyber-threat to Britain was ‘chronic, advanced and persistent’.

GCHQ, the Cheltenham-based intelligence centre, has warned that an attack on nuclear power stations, electricity and computer networks could lead to blackouts where fridges, phones, computers, water networks and transport systems are brought to a halt.

Security officials have also warned that computer hackers could launch computer-generated assaults which could force an airliner packed with people to crash.

A new breed of ‘cyber criminals’ could crack sophisticated on board computer systems and pose a threat to a plane - avoiding the need for any potential murderer to board a plane, it is feared.

Ministers will this month publish the National Security Strategy (NSS) which is expected to highlight the ‘huge’ internet-based potential risks facing Britain because of the online dependence of Whitehall, businesses and individuals.

Individuals creating software viruses or rogue computer programs and emails are likely to be considered a ‘Tier 1’ threat - the most serious.

The figures revealed by Mr Martin relate to attacks or attempted attacks that pass of a threshold of seriousness for GCHQ.

Security officials have also warned that computer hackers could launch computer-generated assaults

That could include targeting critical national infrastructure or significant attacks from key groups such as hostile states or serious organised crime groups.

Cyber-attacks using previously unknown methods to penetrate security systems would also be counted.

Officials also warned that advanced hacking technology is increasingly available online meaning increasing numbers of offenders can launch cyber-attacks.

Simply technology for denial of service attacks – where a computer system is bombarded with messages until it ‘collapses’ – can be bought for a few pounds.

Major attacks are becoming increasingly common. Last month hackers stole the personal details of more than 156,000 customers of the communications company TalkTalk.

Research in the summer revealed that cyber-attackers have hit nine out of 10 major British companies – costing the economy tens of billions of pounds.

Mr Martin issued his warning as GCHQ and the Government launched a £6.5 million Cyber Invest programme, which will work with academic experts and the private sector to support research into cyber-attacks and how best to protect against them.

Cyber-security minister Matthew Hancock told the Information Assurance conference in London that defences around the Government email network is repelling 33,000 attempted attacks every month.